A flow distribution module with a patterned cover plate

ABSTRACT

A flow distribution module ( 1 ) for distributing a flow of fluid over a surface to be cooled is disclosed. The flow distribution module ( 1 ) comprises a housing ( 2 ) and a cover plate ( 3 ). The housing ( 2 ) defines at least one flow cell ( 5 ), the flow cell(s) ( 5 ) being positioned in such a way that a flow of fluid flowing through a flow cell ( 5 ) from an inlet opening ( 6 ) to an outlet opening ( 7 ) is conveyed over the surface to be cooled, each flow cell ( 5 ) being formed to cause at least one change in the direction of flow of the fluid flowing through the flow cell ( 5 ). The cover plate ( 3 ) is arranged adjacent to the flow cell(s) ( 5 ) and defines the surface to be cooled. At least a part of the surface to be cooled defined by the cover plate ( 3 ) is provided with a surface pattern ( 8 ) of raised and depressed surface portions.

CROSS-REFERENCE TO RELATED APPLICATION

This application is entitled to the benefit of and incorporates byreference subject matter disclosed in International Patent ApplicationNo. PCT/EP2013/071006 filed on Oct. 9, 2013 and European PatentApplication 12007006.5 filed Oct. 9, 2012.

FIELD OF THE INVENTION

The present invention relates to a flow distribution module fordistributing a flow of fluid over a surface to be cooled. The flowdistribution module of the invention is capable of cooling the surfacein a very efficient manner.

BACKGROUND

Flow distribution modules f or distributing a flow of fluid over asurface to be cooled, there by providing cooling for the surface, havepreviously been provided. For instance, WO 2005/040709 discloses a flowdistribution unit and cooling unit in which a plurality of flow cellsare arranged to convey a flow of fluid over a surface to be cooled. Theflow cells are connected fluidly in parallel between an inlet manifoldand an outlet manifold, and the flow cells may define meandering flowpaths. DE 202 08 106 U1 discloses a similar cooling device.

In the distribution units disclosed in WO 2005/040709 and DE 202 08 106U1 the surface being cooled is substantially plane.

SUMMARY

It is an object of embodiments of the invent ion to provide a flowdistribution module in which heat transfer from a surface to be cooledto fluid flowing in the flow distribution module is improved as comparedto prior art flow distribution modules.

It is a further object of embodiments of the invention to provide a flowdistribution module in which the risk of clogging of the flowdistribution module is minimised.

It is an even further object of embodiments of the invention to providea flow distribution module in which pressure drop of fluid flowingthrough the flow distribution module is minimised.

The invention provides a flow distribution module for distributing aflow of fluid over a surface to be cooled, said flow distribution modulecomprising:

-   -   a housing defining at least one flow cell, each flow cell having        an inlet opening arranged to receive fluid to the flow cell and        an outlet opening arranged to deliver fluid from the flow cell,        the flow cell(s) being positioned in such away that a flow of        fluid flowing through a flow cell from the inlet opening to the        out let opening is conveyed over the surface to be cooled, each        flow cell being formed to cause at least one change in the        direction of flow of the fluid flowing through the flow cell,    -   a cover plate arranged adjacent to the flow cell(s), said cover        plate defining the surface to be cooled,

-   wherein at least a part of the surface to be cooled defined by the    cover plate is provided with a surface pattern of raised and    depressed surface portions.

The flow distribution module of the invention is adapted to distribute aflow of fluid over a surface to be cooled. Thus, when fluid flowsthrough the flow distribution module, it flows along the surface, andthereby heat is transferred from the surface to the fluid flowing in theflow distribution module. Accordingly, the fluid conveys the heat awayfrom the surface, and the surface is thereby cooled.

The fluid flowing in the flow distribution module may advantageously bea liquid, such as water or a mixture of ethylene-glycol and water. As analternative, the fluid may be a two-phase refrigerant, such as R134a. Asanother alternative, the fluid may be gaseous.

The flow distribution module comprises a housing defining at least oneflow cell. Each flow cell has an inlet opening arranged to receive fluidand an outlet opening arranged to deliver fluid. Accordingly, fluid canbe received at the inlet opening, flow through the flow cell, via a flowpath defined by the flow cell, and finally be delivered from the flowcell at the outlet opening. The flow cell(s) is/are arranged in such away that when fluid flows through the flow cell(s) as described above,the fluid is conveyed over the surface to be cooled. Accordingly, heatis transferred from the surface to the fluid flowing in the flowcell(s).

Each flow cell is formed to cause at least one change in the directionof flow of the fluid flowing through the flow cell. When the directionof flow of the fluid flowing through a flow cell is changed, the fluidis swirled. Thereby the hot fluid, which is in direct contact with thesurface to be cooled, is mixed with the cooler fluid flowing at adistance to the surface to be cooled. This allows the cooling capacityof the fluid to be utilised fully. Furthermore, the swirl provided bythe change in direction of flow of the fluid in itself forces the fluidtowards the surface to be cooled in a beneficial manner. This will bedescribed further below.

Such a change of direction is beneficial to the process of cooling, andit has been found that a significant change of direction is helpful inenhancing cooling. Thus a change in direction of over 20° is beneficial,and one of 180° is particularly beneficial in producing mixing andswirl. Thus the change of direction can be, with benefit, in the range20° to 180°, such as in the range of 30° to 180°, such as in the range90° to 180°. The change of direction can be in the directionperpendicular to the plane of the surface to be cooled, in the directionparallel to the plane of the surface to be cooled, or in a combinationof the two. A change of direction perpendicular to the plane of thesurface to be cooled may, for example, be enabled by the surface patternprovided. A change of direction parallel to the plane of the surface tobe cooled may, for example, be enabled by the design of the flowcell(s), in particular by the distribution of walls which causedeviations in the direction of flow of the fluid over the surface to becooled.

The flow cell(s) may advantageously be formed to cause a plurality ofchanges in the direction of flow of the fluid flowing through the flowcell(s). Thereby the swirl of the fluid is even more significant.

The flow distribution module further comprises a cover plate arrangedadjacent to the flow cell(s). The cover plate defines the surface to becooled. For instance, the surface to be cooled may be a surface of thecover plate which faces the flow cell(s), i.e. which is arrangeddirectly in contact with the fluid flowing in the flow cell(s).

At least a part of the surface to be cooled is provided with a surfacepattern of raised and depressed surface portions. Thereby the surfacearea of the surface to be cooled is enlarged as compared to a similarsurface which is substantially plane. Accordingly, the contact areabetween the surface to be cooled and the fluid flowing in the flowcell(s) is increased, and thereby the transfer of heat from the surfaceto be cooled to the fluid flowing in the flow cell(s) becomes moreefficient.

It should be noted that the raised and depressed surface portions of thesurface pattern are ‘raised’ and ‘depressed’ relative to each other inthe sense that the raised surface portions are arranged further awayfrom a surface of the cover plate arranged opposite to the surface to becooled, than the depressed surface portions. The surface pattern may beprovided in such a manner that the depressed surface portions arearranged at a level corresponding to the level of a part of the surfaceto be cooled which is not provided with the surface pattern, while theraised surface portions protrude outwards from this level. As analternative, the raised surface portions may be arranged at said level,while the depressed surface portions protrude into the cover plate fromthis level. As another alternative, the raised surface portions mayprotrude outwards from said level, while the depressed surface portionsprotrude into the cover plate from said level. This last alternative hasthe distinct advantage that it is possible to generate such a pattern byrelatively small scale movement of material from which the surfacepattern is created. For example, such a pattern may be made by means ofpunching, stamping, rolling or similar techniques in which with in alocal area, a small depression formed in the material is matched by aprotrusion of similar size in close proximity. Such manufacturingtechniques are relatively cheap, and a surface pattern created usingthem is easily and cheaply manufactured at low cost, leading to animproved and competitive product.

In order to utilise the enlarged surface area of the surface to becooled, which is provided by the surface pattern, it must be ensuredthat the fluid flowing in the flow cell(s) is brought into contact withthe entire enlarged surface. Thus, the fluid must be forced ‘into’ thesurface pattern. This can, e.g., be achieved by designing the flowcell(s) in such a manner that the cross sectional area of the flowpath(s) defined by the flow cell(s) is small, thereby forcing the fluidto follow the raised and depressed surface portions closely. However,this has the disadvantage that the risk of clogging of the flow path(s)is very high. Furthermore, a large pressure drop of the fluid flowingthrough the flow cell(s) must be expected.

However, in the flow distribution module according to the invention, theflow cell(s) is/are formed to cause at least one change in the directionof flow of the fluid flowing through the flow cell(s). As describedabove, this causes the fluid to be swirled, and this swirl ensures thatthe fluid is forced towards the surface to be cooled and into thesurface pattern, thereby bringing the fluid into contact with the entireenlarged surface area. Thereby, the enlarged surface area of the surfaceto be cooled can be utilised, while maintaining relatively largedimensions of the flow path(s) defined by the flow cell(s).

Accordingly, the combination of designing the flow cell(s) to provide atleast one change in the direction of flow of the fluid flowing throughthe flow cell(s), and providing the surface pattern of raised anddepressed surface portions on the surface to be cooled, allows efficientheat transfer from the surface to be cooled to the fluid flowing in theflow cell(s), without risking clogging of the flow path(s) of the flowcell(s), and without introducing a large pressure drop of the fluidflowing through the flow cell(s). This is very advantageous.Furthermore, the combination of the increased surface area provided bythe surface pattern, and the mixture of the fluid caused by the swirlimproves the heat transfer of the flow distribution module, and therebythe cooling performance of the flow distribution module.

The surface pattern may, e.g., be provided by means of punching,stamping, rolling or similar techniques. In this case the surfacepattern is formed directly in a surface of the cover plate duringmanufacture of the cover plate.

It should be noted that, even though the description above refers to ‘asurface to be cooled’ and ‘the surface to be cooled’, the flowdistribution module of the invention may be used for cooling two or moresurfaces, each being arranged adjacent to one or more flow cells in anappropriate manner.

The flow distribution module may further comprise an inlet manifold andan outlet manifold, and the housing may define at least two flow cells,the inlet opening of each flow cell being fluidly connected to the inletmanifold and the outlet opening of each flow cell being fluidlyconnected to the outlet manifold, each flow cell thereby establishing afluid connection between the inlet manifold and the outlet manifold.According to this embodiment, the flow cells cover various parts of thesurface to be cooled, and it is thereby possible to provide moreintensive cooling to some parts of the surface than to other parts.

The flow cells may be arranged fluidly in parallel between the inletmanifold and the outlet manifold, the flow cells thereby definingparallel flow paths between the inlet manifold and the outlet manifold.According to this embodiment, each flow cell is directly fluidlyconnected to the inlet manifold via its inlet opening, and directlyfluidly connected to the outlet manifold via its outlet opening. Therebythe fluid entering each of the flow cells has the same temperature. Thisallows uniform cooling to be provided across the surface to be cooled,i.e. temperature variations across the surface can be minimised.

As an alternative, two or more of the flow cells may be arranged fluidlyin series. In this case the inlet opening of a first flow cell may befluidly connected directly to the inlet manifold, the outlet opening ofthe first flow cell may be fluidly connected to the inlet opening of asecond flow cell, and the outlet opening of the second flow cell may befluidly connected directly to the outlet manifold. Thus, the first flowcell is fluidly connected to the outlet manifold via the second flowcell, and the second flow cell is fluidly connected to the inletmanifold via the first flow cell.

The inlet manifold and the outlet manifold may be defined by thehousing. According to this embodiment, the housing, the inlet manifold,the outlet manifold and the flow cells may be formed as a single part,and the cover plate may be mounted on this part, thereby forming aclosed unit with the flow cells and the manifolds arranged inside theclosed unit. This allows the manufacturing costs of the flowdistribution module to be minimised.

At least one flow cell may define a meandering flow path. According tothe this embodiment, the change(s) in direction of flow of the fluidflowing through the flow cell(s) is/are primarily caused by the fluidfollowing the meandering path. As an alternative, the change(s) indirection of flow of the fluid flowing through the flow cell(s) may beobtained in another way.

For instance, each flow cell may comprise a surface arranged oppositeand facing the surface to be cooled, the surface of the flow cell beingprovided with a surface pattern which, e.g., is a mirror image of thesurface pattern provided on the surface to be cooled, or a surfacepattern which is identical or similar to the surface pattern provided onthe surface to be cooled. If the two surfaces are arranged sufficientlyclose to each other, the surface patterns of the surface to be cooledand the surface of the flow cell, respectively, may cooperate to causethe fluid flow to change direction as the fluid flows through the flowcell. In the case that the two surface patterns are identical, thesurface patterns may, e.g., be arranged in such a manner that raisedsurface portions are arranged opposite to each other and depressedsurface portions are arranged opposite to each other. In this case thedistance between the surfaces varies across the surface patterns, andthis variation gives rise to the swirl of the fluid flowing through theflow cell. As an alternative, the surface patterns may be arranged insuch a manner that raised surface portions of one surface pattern arearranged opposite depressed surface portions of the other surfacepattern, and vice versa. In this case the distance between the surfacesis substantially constant across the surface patterns, but the directionof flow of the fluid is changes as the fluid follows the raised anddepressed surface portions. The change in direction of the fluid flowmay occur in a direction towards and away from the surfaces, and/or in adirection substantially parallel to the surfaces, in order to ‘navigate’the fluid around the surface structures defined by the surface patterns.

The surface pattern may define a sub-pattern which is repeated along atleast one direction of the surface pattern. The sub-pattern may berepeated along only one direction of the surface pattern, or it may berepeated along two or more directions of the surface pattern. In thecase that the sub-pattern is repeated along only one direction of thesurface pattern, the surface pattern may be in the form of a corrugatedsurface defining ‘grooves’ and ‘ridges’ arranged alternatingly on thesurface in a manner which resembles a linearly evolving wave front. The‘grooves’ and ‘ridges’ may have substantially sinusoidal shapes,triangular shapes, squared shapes, or any other suitable shapes.

In the case that the sub-pattern is repeated along two or moredirections of the surface pattern, the surface pattern may comprise‘islands’ of raised surface portions surrounded by depressed surfaceportions. In this case the surface pattern may, e.g., comprisestructures of pyramid-like, conical, spherical or hemispherical shape.The raised surface portions and the depressed surface portions may haveessentially the same shape, for instance the raised surface portionbeing pyramids protruding from the surface to be cooled, and thedepressed surface portions being pyramid shaped depressions in thesurface.

-   The surface pattern may even be or comprise fins and/or pins.

In the case that the raised and depressed surface portions have roundedshapes, such as sinusoidal, spherical or hemispherical, the risk ofcorrosion of the surface structure during operation is minimised.

The raised surface portions of the surface pattern may define raisedheight levels and the depressed surface portions of the surface patternmay define depressed height levels. In this case an average heightdifference between the raised height levels and the depressed heightlevels may be within the interval of 0.2 mm to 5 mm, such as within theinterval 0.5 mm to 3 mm, such as within the interval 0.7 mm to 2 mm,such as approximately 1 mm. According to this embodiment, the raisedheight levels could be the levels of top points of pyramids, cones,ridges, hemispheres, etc. forming the raised surface portions. Thus, theraised height levels may be regarded as local maxima of the surfacepattern. Similarly, the depressed height levels could be the levels oflocal minima of the surface pattern, defined by the depressed surfacepattern. Thereby the average height difference between the raised heightlevels and the depressed height levels is a measure for the depth of thesurface pattern, i.e. the typical difference between extremes of thesurface pattern. Thus, according to this embodiment, the depth of thesurface pattern is relatively low, i.e. the structures of the surfacepattern are relatively small. When the structures of the surface patternare small, it is difficult to ensure that the fluid flowing through theflow cell(s) enters into the surface pattern, and it is therefore inparticular an advantage that the fluid is swirled due to the at leastone change of direction of the fluid flow in this case.

Alternatively or additionally, the average height difference between theraised height levels and the depressed height levels may be within theinterval 10% to 60%, such as within the interval 20% to 55%, such aswithin the interval 30% to 50% of an average height of a flow channeldefined by the flow cell(s). According to this embodiment, thedimensions of the structures of the surface structure are significantlysmaller than the typical dimensions of the flow path(s) defined by theflow cell(s). In this case it is also a great advantage that the fluidis swirled due to the at least one change of direction of the fluidflow, thereby forcing the fluid into the surface structure and ensuringthat the enlarged surface area is utilised.

Alternatively or additionally, a median surface level over the areaprovided with the surface pattern may define a surface plane. The medianheight of peaks defined by the raised surface portions, measured fromthe surface plane, may define a peak plane. Similarly, the median depthof troughs defined by the depressed surface portions, measured from thesurface plane, may define at rough plane. In this case the separationbetween the peak plane and the trough plane, measured in a directionnormal to the surface plane, may be with in the interval 0.2 mm to 5 mm,such as within the interval 0.5 mm to 3 mm, such as with in the interval0.7 mm to 2 mm, such as approximately 1 mm. This is also a measure forthe ‘depth’ or roughness of the surface pattern, and the remarks setforth above are equally applicable here.

The cover plate may be mounted on the housing in a substantially fluidtight manner. This may, e.g., be obtained by welding or gluing the coverplate onto the housing. Alternatively, the cover plate may be mounted onthe housing in a reversible manner, e.g. by means of screws or bolts. Inthis case a sealing element, such as an o-ring, may advantageously bearranged between the housing and the cover plate in order to ensure thatthe assembly is fluid tight.

The flow distribution module may further comprise at least one powermodule mounted on a surface the cover plate which is opposite to thesurface having the surface pattern provided thereon. The power modulemay, e.g., be a semiconductor power module. Power modules produce heat.By mounting the power module on the cover plate, the power module can becooled by means of the fluid flowing in the flow cell(s) of the flowdistribution module.

The power module(s) may be arranged in a region of the cover plate wherethe surface pattern is provided. Thereby the power module is efficientlycooled, as described above.

The surface to be cooled may comprise two or more separate regions, eachbeing provided with a surface pattern, the patterned regions beingseparated by regions with no surface pattern. In this case two or morepower modules, or other heat producing elements, may be mounted on thecover plate, and each power module may be mounted at a positioncorresponding to the position of a patterned region. Furthermore, a zonealong the edge of the cover plate may be left without surface pattern inorder to ensure that a proper sealing can be provided between thehousing and the cover plate.

At least the cover plate may be made from a metal, such as copper.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in further detail with reference tothe accompanying drawings in which

FIG. 1 is a perspective view of a flow distribution module according toan embodiment of the invention,

FIG. 2 is a perspective view of a housing for a flow distribution moduleaccording to an embodiment of the invention,

FIG. 3 is a perspective view of a cover plate for a flow distributionmodule according to an embodiment of the invention,

FIG. 4 is a perspective view of a part of a cover plate for a flowdistribution module according to an alternative embodiment of theinvention,

FIG. 5 illustrates a surface pattern for the cover plates of FIG. 3 or4,

FIGS. 6-8 are cross sectional views of a flow distribution moduleaccording to a first embodiment of the invention, seen from variousangles, and

FIG. 9 is a cross sectional view of a flow distribution module accordingto a second embodiment of the invention.

FIG. 10 is a perspective view of a cover plate for a flow distributionmodule according to a third embodiment of the invention.

FIG. 11 is a perspective view of a housing for a flow distributionmodule according to a third embodiment of the invention.

FIG. 12 as a cross-sectional view of a flow distribution moduleaccording to a third embodiment of the invention and showing theplacement of the housing shown in FIG. 11 in relation to the cover plateshown in FIG. 10.

DETAILED DESCRIPTION

FIG. 1 is a perspective view of a flow distribution module 1 accordingto an embodiment of the invention. The flow distribution module 1comprises a housing 2 and a cover plate 3 mounted on the housing 2 in asubstantially fluid tight manner. The housing 2 defines one or more flowcells (not visible) arranged to cause fluid to flow over a surface ofthe cover plate 3 which faces the interior of the housing 2. This willbe described further below.

Six heat producing power modules 4 are mounted on the cover plate 3. Thepower modules 4 are thereby cooled by means of fluid flowing through theflow cell(s) defined by the housing 2.

FIG. 2 is a perspective view of a housing 2 for a flow distributionmodule according to an embodiment of the invention. The housing 2 ofFIG. 2 may, e.g., be used for the flow distribution module 1 of FIG. 1.

The housing 2 defines a plurality of flow cells 5. Each flow cell 5comprises an inlet opening 6, which is fluidly connected to an inletmanifold (not visible), and an outlet opening 7, which is fluidlyconnected to an outlet manifold (not visible). Thus, each flow cell 5establishes a flow path between the inlet manifold and the outletmanifold, and the flow paths are arranged fluidly in parallel betweenthe inlet manifold and the outlet manifold.

Each of the flow cells 5 defines a meandering flow path. Thereby fluidflowing through a flow cell 5 from the inlet opening 6 to the outletopening 7 is caused to perform a plurality of changes in the directionof flow of the fluid. As described above, this causes the fluid to‘swirl’, thereby forcing the fluid towards a cover plate to be mountedon the housing 2 in such a manner that it covers the flow cells 5, andin such a manner that a surface of the cover plate is arranged in directcontact with fluid flowing through the flow cells 5.

FIG. 3 is a perspective view of a cover plate 3 for a flow distributionmodule according to an embodiment of the invention. The cover plate 3 ofFIG. 3 may, e.g., be used in the flow distribution module 1 of FIG. 1,and/or it may be mounted on the housing 2 of FIG. 2 in order to form aflow distribution module.

A centre region of the cover plate 3 is provided with a surface pattern8 of raised and depressed surface portions. Thereby the surface area inthe region of the surface pattern 8 is enlarged, and it is thereforepossible to provide efficient cooling to heat producing elements, suchas the power modules 4 shown in FIG. 1, mounted on the opposite side ofthe cover plate 3.

When the cover plate 3 is mounted on a housing in order to form a flowdistribution module, it is mounted in such a manner that the surfacepattern 8 faces the flow cell(s), e.g. the flow cells 5 shown in FIG. 2,defined inside the housing. Thereby the fluid flowing through the flowcell(s) is brought into contact with the surface pattern 8. As describedabove, the fluid flowing through the flow cell(s) is caused to swirl dueto one or more changes in the direction of flow of the fluid, e.g. bymeans of the meandering flow paths shown in FIG. 2. The swirl of thefluid forces the fluid into the surface pattern 8, thereby ensuring thatit is brought into contact with the entire enlarged surface area.Furthermore, this is achieved without having to make the dimensions ofthe flow path(s) small. This is an advantage, because small flow pathsintroduce the risk of clogging of the flow paths, and introduce a largepressure drop across the flow cell.

FIG. 4 is a perspective view of a part of a cover plate 3 for a flowdistribution module according to an alternative embodiment of theinvention. The cover plate 3 of FIG. 4 is very similar to the coverplate 3 of FIG. 3, and the remarks set forth above are therefore equallyapplicable here.

Whereas the cover plate 3 of FIG. 3 comprises a single region beingprovided with surface pattern 8, the cover plate 3 of FIG. 4 is providedwith several regions, each being provided with a surface pattern 8. Onesurface pattern 8 is shown fully, and a part of the next surface pattern8 can be seen. The cover plate 3 of FIG. 4 may have a number of heatproducing elements, such as power modules, mounted on the opposite sideof the cover plate 3, each heat producing element being mounted in aregion corresponding to a region being provided with a surface pattern8. Thereby the surface patterns 8 are only provided in the regions wherecooling is required, and the remaining parts of the cover plate 3 areleft substantially plane.

FIG. 5 illustrates a surface pattern 8 for the cover plates 3 of FIG. 3or 4. The surface pattern 8 comprises a plurality of pyramids withinverted pyramid shapes there between. The pyramids form raised surfaceportions, and the inverted pyramid shapes form depressed surfaceportions of the surface pattern 8. The surface pattern 8 illustrated inFIG. 5 increases the surface area of the surface by a fact or ‘12.

FIGS. 6-8 are cross sectional views of a flow distribution module 1according to a first embodiment of the invention, seen from variousangles. The flow distribution module 1 comprises the housing 2 of FIG. 2and the cover plate 3 of FIG. 3 or the cover plate 3 of FIG. 4. Thecover plate 3 is mounted on the housing 2 in a substantially fluid tightmanner, and in such a manner that the surface pattern 8 of the coverplate 3 faces the flow cells 5 of the housing 2.

It is clear from FIGS. 6-8 that the height of the flow paths defined bythe flow cells 5 is significantly larger than the depth or roughness ofthe surface pattern 8. Thereby the pressure drop of fluid flowingthrough the flow cells 5 is minimised. Furthermore, the risk of cloggingof the flow cells 5 is minimised.

However, the swirl of the fluid provided by the plurality of changes ofdirection of the fluid flow, caused by the meandering flow path, ensuresthat the fluid is forced into the surface pattern 8, thereby bringing itinto contact with the entire enlarged surface area. As a consequence,the surface of the cover plate 3 being provided with the surface pattern8 can be efficiently cooled.

In FIGS. 6-8 it appears that the surface pattern 8 is provided over theentire area covered by the flow cells 5. It could, however, be envisagedthat the surface pattern 8 is removed at the positions corresponding tothe side walls of the meandering structure of the flow cells 5. Therebyit is possible to design a possible gap between the surface to be cooledand the sidewalls of the flow cells 5 in such a manner that a desiredbypass flow is provided. Thereby the cooling performance of the flowdistribution module 1 can be optimised, while the pressure drop of fluidflowing through the flow distribution module 1 is minimised. As analternative, the side walls of the meandering structure of the flowcells 5 could be designed in such a manner that they follow the surfacepattern 8 of the surface to be cooled, thereby provided appropriatebypass passages.

FIG. 9 is a cross sectional view of a flow distribution module 1according to a second embodiment of the invention. In the embodiment ofFIG. 9, the cover plate 3 is identical or similar to the cover plate 3of the embodiment of FIGS. 6-8, and it will therefore not be describedin detail here.

The housing 2 defines a flow cell comprising a surface which is providedwith a surface pattern which is essentially a mirror image of thesurface pattern 8 provided on the cover plate 3. When fluid is flowingin the flow cell, it is forced to follow passages defined between raisedsurface portions of the surface pattern 8 provided on the cover plate 3and the raised surface portions of the surface pattern 9 provided in theflow cell. Thereby the fluid is forced to perform a plurality of changesin the direction of flow. Accordingly, the fluid is forced into thesurface pattern 8 provided on the cover plate 3, and thereby the fluidis brought into contact with the entire enlarged surface area providedby the surface structure 8, and ensuring an efficient cooling of thecover plate 3. This is obtained without having to decrease the distancebetween the surface patterns 8, 9, thereby increasing the risk ofclogging and excessive pressure drop of the fluid flowing through theflow cell.

In the flow distribution module 1 of FIG. 9, the raised surface portionsof surface pattern 8 are arranged opposite raised surface portions ofsurface pattern 9, and depressed surface portions of surface pattern 8are arranged opposite depressed surface portions of surface portions ofsurf ace pattern 9. Thereby the distance between the surfaces, andthereby the dimensions of the flow path defined by the flow cell, variesacross the surf ace patterns 8, 9. This variation provides the ‘swirl’of the fluid flowing through the flow cell.

As an alternative, the surface patterns 8, 9 could be shifted relativeto each other, in such a way that the raised surface portions of surfacepattern 8 could be arranged opposite depressed surface portions ofsurface pattern 9, and depressed surface port ions of surface pattern 8could be arranged opposite raised surface portions of surface pattern 9.In this case the ‘swirl’ of the fluid is provided by the fluid‘navigating’ around the raised surface portions of the surface patterns8, 9. This ‘navigation’ could take place in a direction towards and awayfrom the surface patterns 8, 9, and/or in a direction substantiallyparallel to the surface patterns 8, 9, i.e. sideways through the flowcell.

FIG. 10 is a perspective view of a cover plate 3 for a flow distributionmodule according to a third embodiment of the invention. In this figureit can be seen that the surface pattern 8 comprises a repeated set ofidentical units, each of those units comprising an area of indentation9, where the surface is below the surrounding surface of the plate,adjacent to an area of protuberance 10, where the surface is above thesurrounding surface of the plate 8. The volumes of the indentation andprotuberance are approximately the same. Such a pattern unit iswell-suited to be formed by, for example, a punch pushed at an angleinto the initial surface and thereby pushing material from the createdindentation up into the created protuberance. Such a three-dimensionalpattern is well-suited to manufacturing processes involving punching,stamping, rolling a similar techniques, and since such manufacturingprocesses are cheap and easily available, they form a advantageous meansof creating the shown surface pattern, a pattern which greatly increasesthe heat transfer characteristics of a flow distribution module.

FIG. 11 is a perspective view of a housing 2 for a flow distributionmodule according to a third embodiment of the invention, and FIG. 12shows a cross-sectional view of this housing 2 placed adjacent to thecover plate 3 shown in FIG. 10, thus forming a flow distribution module1 according to the third embodiment of the invention. The housing 2defines a plurality of flow cells 5. Each flow cell 5 comprises an inletopening 6, which is fluidly connected to an inlet manifold (notvisible), and an outlet opening 7, which is fluidly connected to anoutlet manifold (not visible). Thus, each flow cell 5 establishes a flowpath between the inlet manifold and the outlet manifold, and the flowpaths are arranged fluidly in parallel between the inlet manifold andthe outlet manifold.

Each of the flow cells 5 defines a meandering flow path. Thereby fluidflowing through a flow cell 5 from the inlet opening 6 to the outletopening 7 is caused to perform a plurality of changes in the directionof flow of the fluid. As described above, this causes the fluid to‘swirl’, thereby forcing the fluid towards a cover plate to be mountedon the housing 2 in such a manner that it covers the flow cells 5, andin such a manner that a surface of the cover plate is arranged in directcontact with fluid flowing through the flow cells 5.

Although various embodiments of the present invention have beendescribed and shown, the invention is not restricted thereto, but mayalso be embodied in other ways within the scope of the subject-matterdefined in the following claims.

What is claimed is:
 1. A flow distribution module for distributing aflow of fluid over a surface to be cooled, said flow distribution modulecomprising: a housing defining at least one flow cell, each flow cellhaving an inlet opening arranged to receive fluid to the flow cell andan outlet opening arranged to deliver fluid from the flow cell, the flowcell(s) being positioned in such away that a flow of fluid flowingthrough a flow cell from the inlet opening to the outlet opening isconveyed over the surface to be cooled, each flow cell being formed tocause at least one change in the direction of flow of the fluid flowingthrough the flow cell, a cover plate arranged adjacent to the flowcell(s), said cover plate defining the surface to be cooled, wherein atleast a part of the surface to be cooled defined by the cover plate isprovided with a surface pattern of raised and depressed surfaceportions.
 2. The flow distribution module according to claim 1, furthercomprising an inlet manifold and an outlet manifold, wherein the housingdefines at least two flow cells, the inlet opening of each flow cellbeing fluidly connected to the inlet manifold and the outlet opening ofeach flow cell being fluidly connected to the outlet manifold, each flowcell thereby establishing a fluid connect on between the inlet manifoldand the outlet manifold.
 3. The flow distribution module according toclaim 2, wherein the flow cells are arranged fluidly in parallel betweenthe inlet manifold and the outlet manifold, the flow cells therebydefining parallel flow paths between the inlet manifold and the outletmanifold.
 4. The flow distribution module according to claim 2, whereinthe inlet manifold and the outlet manifold are defined by the housing.5. The flow distribution module according to claim 1, wherein at leastone flow cell defines a meandering flow path.
 6. The flow distributionmodule according to claim 1, wherein the surface pattern defines asub-pattern which is repeated along at least one direction of thesurface pattern.
 7. The flow distribution module according to claim 1,wherein the raised surface portions of the surface pattern define raisedheight levels and the depressed surface portions of the surface patterndefine depressed height levels, and wherein an average height differencebetween the raised height levels and the depressed height levels iswithin the interval of 0.2 mm to 5 mm.
 8. The flow distribution moduleaccording to claim 1, wherein the raised surface portions of the surfacepattern define raised height levels and the depressed surface portionsof the surface pattern define depressed height levels, and wherein anaverage height difference between the raised height levels and thedepressed height levels is with in the interval 10% to 60% of an averageheight of a flow channel defined by the flow cell(s).
 9. The flowdistribution module according to claim 1, wherein the cover plate ismounted on the housing in a substantially fluid tight manner.
 10. Theflow distribution module according to claim 1, further comprising atleast one power module mounted on a surface the cover plate which isopposite to the surface having the surface pattern provided thereon. 11.The flow distribution module according to claim 10, wherein the powermodule(s) is/are arranged in a region of the cover plate where thesurface pattern is provided.
 12. The flow distribution module accordingto claim 3, wherein the inlet manifold and the outlet manifold aredefined by the housing.
 13. The flow distribution module according toclaim 2, wherein at least one flow cell defines a meandering flow path.14. The flow distribution module according to claim 3, wherein at leastone flow cell defines a meandering flow path.
 15. The flow distributionmodule according to claim 4, wherein at least one flow cell defines ameandering flow path.
 16. The flow distribution module according toclaim 2, wherein the surface pattern defines a sub-pattern which isrepeated along at least one direction of the surface pattern.
 17. Theflow distribution module according to claim 3, wherein the surfacepattern defines a sub-pattern which is repeated along at least onedirection of the surface pattern.
 18. The flow distribution moduleaccording to claim 4, wherein the surface pattern defines a sub-patternwhich is repeated along at least one direction of the surface pattern.19. The flow distribution module according to claim 5, wherein thesurface pattern defines a sub-pattern which is repeated along at leastone direction of the surface pattern.
 20. The flow distribution moduleaccording to claim 2, wherein the raised surface portions of the surfacepattern define raised height levels and the depressed surface portionsof the surface pattern define depressed height levels, and wherein anaverage height difference between the raised height levels and thedepressed height levels is within the interval of 0.2 mm to 5 mm.